This invention relates to circuits and methods for voltage regulation and, more particularly, to such circuits and methods as applied to regulation of the output voltage of electric power sources.
Typical electric generator voltage regulators include a sensing circuit which senses a high power AC or DC output voltage of the generator and produces a DC output signal proportional to the sensed voltage. The sensing circuit output signal is subtracted from a reference signal to develop an error signal proportional to the difference between the actual generator output and a desired generator output. A compensator modifies the loop gain of the voltage regulator feedback control loop to achieve the desired transient response.
The output of the compensator is amplified to produce exciter field current for the generator. The output of the generator is proportional to the exciter field current. Because of the power levels required, switching amplifiers are typically used to produce the exciter field current. These amplifiers require a pulse width modulated input, which is produced by amplifying the error signal.
The pulse width modulated output required from the error amplifier imposes limitations on the sensing circuit. Since the gain of the error amplifier is determined by the ripple in the output of the sensing circuit, this ripple must be controlled to maintain constant gain of the system.
The limitation on the sensing circuit can be avoided if the regulator power amplifier can operate with a linear error signal, such that pulse width modulated error signals are not required. The present invention provides a circuit and method for sensing and control of generator output voltage which optimizes the system performance while utilizing linear error output signals to control the generator excitation.